Update:
I finally installed this on my car. I can hold boost all the way with no problem now. Another problem I was having was with my 2-step launch control. The car would not build any boost even at 6k rpm. Just tested this and easily build boost off the line.
Proving further that the stock wastegate door in the turbine housing is being forced open prematurely by exhaust pressure. Porting the wastegate can just make this even worse. EBC's will NOT fix this, at all.